On 1 Jan 20X5, a business purchased a non-current asset costing 50000 with an estimated life of 5 years and no residual value. After 3 years, the business decided that the useful life of the asset has been underestimated, and it still had 4 more years in use to come. What is the depreciation charge on the year ended 31 Dec 20X8? Assuming that the business uses a straight-line method of depreciation.